Fluorinated organic compounds



mite tates This invention relates to the perfluorinated conjugated diene perfiuorovinylcyclobutene and homopolymers and copolymers thereof. The perfluorinated conjugated diene, perfiuorobutadiene CFFCFCF=C 3 is well known and many attempts have been made to polymerize this compound to produce useful polymers. It has been found to polymerize, however, only with great difficulty. For example, the polymerization of hexafluorobutadiene to high molecular weight polymers required extremely high pressures of the order of 225,000 lbs/in. gage as reported by Slesser and Schram, Preparation, Properties, and Technology of Fluorine and Organic Fluoro Compounds, McGraw- Hill, 1951, pages 625-626.

In accordance with the present invention a new conjugated perfiuorinated diene has been discovered, namely perfluorovinylcyclobutene having the formula:

CF;=CFC=CF Fr-( J F2 which polymerizes with ease to form materials.

In accordance with the invention this new diene is prepared by the dehalogenation of the compound l-iodo- 2-(1,2-dichloro-1,2,2-trifluoroethyl) perfiuorocyclobutane:

CF2 F1 Loss of the two chlorines, the iodine atom, and the adjacent fluorine, produces the desired conjugated diene. The dehalogenation of the iodide to produce the desired diene is preferably carried out with the use of an excess of metallic zinc in a suitable medium, preferably acetic valuable polymeric acid, or other mediums such as acetamide, ethanol, or di- I oxane. The reaction is preferably carried out at room temperature to the reflux temperature of the reaction mixture.

The intermediate iodide, 1-iodo-2(1,2-dichloro-l,2,2- trifluoroethyl) perfluorocyclobutane, may in turn be prepared by heating 1,2-dichloro-1,1,2-trifluoroiodoethane, CF CICFCII, with perfluorocyclobutene C F g-OF 2 under pressures from 1000 to 10,000 lbs/in. gage and preferably from 3000 to 7000 lbs/in. gage and at temperatures of from 15 to 350 C. and preferably from 200 to 300 C. for reaction periods of a few hours to as much as two Weeks and using molar ratios of iodide to :olefin ranging from about 1:2 to 20:1. As well as producing the desired iodide in which one mole of CF CICFCII reacts with one mole of perfluorocyclobutene, there is also obtained from this reaction higher products resulting from a telomerization reaction having the formula:

CFzOlCFCl OF-OF I CF' (|3F2 L containing repeating perfluorocyclobutyl OF-CF [(EFz-CFz] radicals. The letter 11 indicates the number of repeating atent Oflice 3,046,261 Patented July 2 19 62 units in the telomer chain. The higher telomers tend to be produced with low iodide to olefin ratios, with longer reaction periods, and at higher temperatures. The value of n may range from 2 to as high as 10 for example. While the desired iodide resulting from the reaction of one mole of CFgClCFClI with one mole of perfluorocyclobutene may be separated from the higher telomers by fractional distillation, it is, of course, preferred to operate the reaction under conditions which provide a maximum yield of the 1:1 adduct and a minimum yield of the higher telomer s. In general, a maximum yield of the desired 1:1 adduct is obtained by using an excess of the iodide CF ClCFClI.

The following example illustrates the above method for preparing perfluorovinylcyclobutene:

Example 1 (a) PREPARATION OF CFzOlCFCl-CFCFI C F r-C F 2 A 300 milliliter Monel metal autoclave is charged with 265 grams of CF ClCFClI and then is charged by vacuum gaseous transfer with 202 grams of perfluorocyclobutene. The autoclave is sealed and heated while shaking for 158 hours at 225 C. The initial pressure of 5250 lbs/in. gage (at 225 C.) drops during the reaction period to 3825 lbs/in. gage. The autoclave is cooled to room temperature and vented. The reaction products are filtered to remove a small amount of iodine and the filtrate is distilled under vacuum and the following fractions obtained:

(a) Unreacted CF CICFCII is removed at a pressure of mm. Hg at a temperature of 37 to 45 C.

(b) 50 grams of OFzOlCFCl-CF-CFI OFr-C F having a boiling range 61 to 66 C. at 23 mm. Hg and a refractive index n 1.4073. Analysis of this fraction is as follows: Calculated for C CI F I, C, 16.3; H, 0.0; I, 28.8. Found, C, 16.6; H, 0.0; I, 28.4.

(c) 14.4 grams of telomer of the formula:

CFzClOFCl CF-CF I OFT-OFiJi having a boiling range of 73 to 79 C. at 5 to 6 mm. Hg and a refractive index n 1.3963. Analysis of this fraction is as follows: Calculated for C CI F I, C, 19.9; H, 00. Found, C, 19.4; H, 0.0.

(d) 6 grams of a viscous oil consisting of higher telomers of the formula:

OFgOlCFCl OF-CF I ('JF2CF2 L where the value of n is greater than 2.

(b) DEHALOGENATION OF CF2ClCFOlOF-CFI or -0F,

(JFlO10Fo1oFoFI CFZOFZ is added to the flask drop by drop. Refluxing is continued for 4 additional hours after which the flask is cooled and the liquid decanted and diluted with water.

3 An oil layer separates which is then combined with the liquid condensed in the Dry Ice-acetone trap. The combined fraction is neutralized with aqueous sodium carbonate solution and washed with water. On distillation there is obtained 4.5 grams of product which on refractionation has a boiling point of 59 to 61 C. consisting of the conjugated diene:

CFq=CF-C|)=CF CF3CF2 The infrared spectrum of this diene shows absorption peaks at 5.69 and 5.86;]. indicating the presence of conjugated double bonds. There is no C-H absorption band. Elemental analysis and molecular weight determinations were made on this diene with the following results. Calculated for C 1 C, 32.15; H, 0.0%; molecular Weight, 224. Found, C, 32.15; H, 0.0; molecular weight, 223.2. A second method for the preparation of perfluorovinylcyclobutene CFz=CF(|3-=-(|3F CF2CF2 is by the dehalogenation of the compound 1-iodo-2-trifluorovinyl-perfluorocyclobutane The dehalogenation of this compound may be carried out in the same manner as the dehalogenation of l-iodo- 2(1,Z-dichlorotrifiuoroethyl) perfluorocyclobutane, that is by the use of metallic zinc in a suitable medium such as acetic acid. Loss of the iodine atom and the fluorine adjacent to the vinyl group gives the desired conjugated diene.

The above iodide may in turn be prepared by the addition of CF =CFI to perfluorocyclobutene in accordance with the following reaction:

The above reaction is carried out by heating the reactants under pressures of from 1000 to 10,000 lbs./in. gage and preferably from 3000 to 7000 lbs./in. gage and the temperatures of from 150 C. to 350 C. and preferably from 200 C. to 300 C. for reaction periods of a few hours to e.g. two weeks, using molar ratios of of from about 1:2 to 20: 1. As in the case of the addition of CF ClCFClI to perfluorocyclobutene higher molar ratios of CF =CFl to perfluorocyclobutene tend to favor the formation of the desired 1:1 adduct and a minimum amount of higher telomers of the formula:

LCFTCF L where the value of n may range, for example, from about 2 to 10. The desired 1:1 adduct may be separated from these telomers by fractional distillation.

The following example illustrates the preparation of the diene:

by the foregoing method.

Example 2 A 300 milliliter Monel autoclave fitted with a glass liner is loaded With 104 grams (0.5 mole) of CF =CFI after which 48.6 grams (0.3 mole) of perfluorocyclobutene is introduced by vacuum gaseous transfer. The autoclave is sealed and heated with shaking for 130 hours at 230 C. at autogenous pressure. After cooling the autoclave to room temperature and venting, the liquid contents are filtered and fractionated. The compound CF2=CF-CF-CFI is obtained together with higher telomers of the formula where the value of n is 2 and higher.

The compound is dehalogenated by treatment with an excess of metallic zinc in glacial acetic acid in the manner described in Example 1 for the dehalogenation of out-01,

to produce the conjugated diene CFz==CF-C:OF

The perfluorinated conjugated diene CFz=CF-C=CF OFT-01% readily homopolymerizes, and also copolymerizes with copolymerizable ethylenically unsaturated compounds to produce polymeric materials having in some instances 'elastomeric properties and having high chemical and thermal stability. The ease with which this diene polymerizes is evidenced by the fact that it may be polymerized at atmospheric pressures by ultraviolet light irradiation or by polymerization in the presence of catalysts such as organic peroxides at relatively low pressures.

In carrying out polymerizations by ultraviolet light irradiation, the polymerization is most conveniently carried out at relatively low temperatures, e.g. 0 to C. using reaction periods ranging from e.g. from onehalf to 300 hours and pressures which may range from atmospheric to any desired pressure.

Suitable free-radical producing polymerization catalysts which may be employed in carrying out the homopoly- 'merization or copolymerization of the diene of the invention include organic catalysts such as benzoyl peroxide, acetyl peroxide, trichloroacetyl peroxide, azodiisobutyronitrile, di-tertiary butyl peroxide, or dipropionyl peroxide; alkyl peroxides such as diethyl peroxide or tertiary butyl hydroperoxide. Suitable in organic peroxides include e.g. barium peroxide, zinc peroxide, or the like which may be used alone or in conjunction with an anhydride of an organic acid; peroxy acids or their salts, e.g. persulfuric acid, ammonium persulfate, potassium persulfate, potassium percarbonate, potassium perphosphate, or sodium perborate. Other suitable polymerization catalysts include e.g. hydrazine salts, such as hydrazine sulfate, and amine oxides such as trimethyl amine oxide.

If desired, buffers may be employed such as sodium pyrophosphate, sodium acid phosphate, sodium bicarbonate, sodium carbonate, or sodium acetate in conjunction with the catalyst particularly where aqueous polymerization media are used.

Promoters may also be employed, if desired, along with the catalyst, such as a reducing agent in conjunction with a peroxy catalyst in a so-called redox polymerization system. Suitable reducing agents include, for example, reduced iron salts such as ferrous ammonium sulfate, sodium sulfite, sodium bisulfite, sodium hydrosulfite, and sodium thiosulfate and the like. If desired, the molecular weight of the polymer may be controlled by addition of regulators such as long chain mercaptans, e.g. tertiary dodecyl mercaptan.

While the amount of catalysts employed is not critical, it should generally be employed in an amount of at least 0.005% based on the weight of the monomer and generally not more than about 5% on the same basis. Usually, the preferred concentration of the catalyst will range from about 0.01% to 3% by weight based on the total weight of monomer.

The polmerization may be carried out at low pressures, preferably ranging from atmospheric to 1000 lbs/in. and more usually from 50 pounds to 500 lbs./in. although higher pressures may be employed if desired. Moderate reaction temperatures ranging from -30 C. to 150 C. and more usually from C. to 100 C. are generally suitable when free radical forming polymerization catalysts are used. Reaction time is not critical, longer reaction periods generally favoring higher conversions. Usually, the practicable reaction periods will range from minutes to a day.

A preferred polymerization procedure involves polymerization in the presence of water using a free radical forming catalyst such as potassium persulfate and deoxygenated water, and desirably an emulsifying agent such as sodium lauryl sulfate or a perfluoro or perfiuorochloro acid having six or more carbon atoms. This mixture is charged to a reactor after which the monomer is intro-- duced, erg. by vacuum gaseous transfer, taking care to exclude oxygen, the reactor then being closed and heated with agitation for a reaction period e.g. one-half to 24 hours at a temperature e.g. 0 C. to 100 C. providing a good conversion of the monomer to polymer.

The following examples illustrate the preparation of the homopolymer.

Example 3 In to an 8 mm. Vycor (96% silica glass) tube there is introduced 0.5 gram of perfluorovinylcyclobutene after which the tube is sealed in vacuum and placed about 3 centimeters from an ultraviolet light source. The tube is irradiated for 3 weeks at room temperature. The solid polymer is removed from the tube and heated in a vacuum oven (operating at about 29 inches H O) at a temperature of 55 to 70 C. for 4 hours. Analysis of the polymer shows that it contains 31.8% carbon as compared to a theoretical carbon content for (C 1 of 32.15%.

Example 4 Thirty grams perfiuorovinylcyclobutene, 0.4 gram C F COONH and a solution consisting of 1 gram K-ZSZOB, gram N34P207'10H20, gram N32S03 in 80 ml. distilled and deoxygenated water are placed in a 7 ounce bottle which is then purged with nitrogen and capped. The bottle is rotated end over end in a water bath at 60 C. for hours. The contents are removed, cooled at -15 C. for 15 hours and then warmed to room temperature. The precipitated polymer polyperfluorovinylcyclobutene is Washed thoroughly with water and dried in vacuum at 75 C.

The diene of the invention readily forms copolymers of valuable properties with copolymerizable ethylenically unsaturated compounds. Preferred comonomers are ethylenically unsaturated compounds having from 2 to 10 carbon atoms, particularly halogenated and more especially fluorinated compounds of this type. A particularly valuable group of comonomers are the haloethylenes such as CHFOFZ, CF CE, CF CFCI, CF CCI CF CHCI, CF =CFH, CH =OHCL and CH =CHE Particularly preferred among the haloethylenes as comonomers are vinylidene fluoride, tetrafluoroethylene and chlorotrifluoroethylene.

Other preferred comonomers include particularly compounds having terminal double bonds such as perfluoropropene, perfluorobutene-l, perfiuoroisobutylene and the like; vinyl others, such as ethylvinyl ether, tn'fluoroethylvinyl ether, acrylates, methacrylates, styrene, acrylonitrile and the like.

Other comonomers that may be polymerized with the diene of the invention include epoxides such as ethylene oxide, particularly the 1,2-epoxides; haloethylenes such as OFCl=CFCl, CHF=CFC1; internally double bonded olefins such as perfluorobutene-Z; and but-adienes such as Z-methylbutadiene and halogenated butadienes such as 2- chlorobutadiene and fiuoroor fluorochlorobutadienes.

The copolymerization of the diene of the invention with such comonomers may be carried out using a wide variety, of ratios of perfiuorovinylcyclobutene to the other monomer. Generally, however, the weight ratio of perfluorovinylcyclobutene to the other monomer Will range from about 95:5 to 5:95 and inmost cases from :15 to 15:85. If desired, a mixture of two or more different comonomers may be copolyrnerized with perfluorovinylcyclobutene to form, for example a terpolymer.

Example 5 A Vycor tube is charged with approximately .2 gram of perfluorovinylcyclobutene and 1 gram of trifluoroethylvinyl ether, CF CH OCH=CH after which the tube is sealed in vacuum. The tube and contents are then placed about 3 centimeters from an ultraviolet light source and irradiated for 24 hours. The tube is then cooled, opened and vented, and the resulting polymer product is heated in vacuum at 50 C. for 5 hours. Analysis of the polymer shows that it contains 36.7% carbon indieating the presence of 86.6 mole percent trifluoroethyl-.

vinyl ether and 13.4 mole butene in the polymer.

The homopolymers and copolymers prepared from perfluorovinylcyclobutene are useful in applications where properties such as chemical inertness and non-flammability are important. The low molecular Weight polymers which may be liquids at normal temperatures are useful as dielectric fluids, lubricants and hydraulic fluids particularly in applications where exposure to chemically corrosive conditions is involved. The higher molecular weight polymers are useful for the production of films, fibers, gaskets, electrical insulation and the like.

I claim:

1. Conjugated perfluorovinylcyclobutene.

2. The compound percent of perfluorovinylcyclo- 3. The method for preparing the diene which comprises dehalogenating the compound CF2C1OFC1-CF=OFI cry-om in the presence of a metallic halogen acceptor.

4. The method for preparing the diene 012:0 F-C=CF orhom which comprises dehalogenating the compound oFl=oF-or=o1 r c Fl-o F2 in the presence of a metallic halogen acceptor.

5. Polymeric perfluorovinylcyclobutene. 6. Polymers of the compound Fz=C FO=C F OFT-om 7. Homopolymers of conjugated per fiuorovinylcyclobutene.

8. Homopolymers of the compound CF =CFC==CF CF2-CF2 9. The method of polymerizing 0 13:0 F-C===C F CFzCFi which comprises heating said diene while in contact with a peroxy polymerization catalyst.

10. The method of polymerizing the compound which comprises exposing said diene to ultraviolet light irradiation.

11. Copolymers of conjugated perfluorovinylcyclobutene and copolymerizable ethylenically unsaturated compounds, in which the weight ratio of perfluorovinylcyclobut-ene to the other monomer is in the range of from about 95:5 to 5:95.

12. Copolymers of conjugated perfluorovinylcyclobutene and haloethylenes, in which the weight ratio of perfluorovinylcyclobutene to the other monomer is in the range of from about 95:5 to 5:95.

13. Copolymers of conjugated perfluorovinyloyclobutene and fluorinated copolymerizable ethylenically unsaturated compounds, in which the weight ratio of perfiuorovinylcyclobutene to the other monomer is in the range of from about :5 to 5:95.

14. Copolymers of conjugated perfluorovinylcyclobutone and vinylidene fluoride, in which the weight ratio of perfluorovinylcyclobutene to the other monomer is in the range of from about 95 :5 to 5:95.

15. Copolymers of conjugated per fluorovinylcyclobutene and tetrafluoroethylene, in which the weight ratio of perfluorovinylcyclobutene to the other monomer is in the range of from about 95 :5 to 5:95.

16. Copolymers of conjugated perfluoroyinylcyclobutene and ohlorotrifluoroethylene, in which the weight ratio of perfluorovinylcyclobutene to the other monomer is in the range of from about 95:5 to 5:95.

17. Copolymers of conjugated perfluorovinylcyolobutene and 2,2,2-trifiuoroethy1 vinyl ether, in which the weight ratio of perfluorovinylcyclobutene to the other monomer is in the range of from about 95:5 to 5:95.

References Cited in the file of this patent UNITED STATES PATENTS Barrick Feb. 22, 1949 OTHER REFERENCES 

1. CONJUGATED PERFLUOROVINLCYOBUTENE. 